It is modern practice, for safety reasons, to incorporate both a main and a reserve canopy in a parachute assembly intended for personal use. The reserve canopy provides a fail-safe measure in case the main canopy should malfunction for any reason. Thus, should the main canopy fail to open fully, for example, the parachutist would disconnect the main canopy from its harness and release the reserve canopy from the container. Normally the reserve canopy is stored in a separate compartment from that which stores the main canopy or it may be stored in a separate container.
It is generally necessary that, in case of a malfunction, the main canopy be disconnected completely from its harness before the reserve canopy is released. Otherwise there is the serious danger that the two may entangle, with fatal results. On the other hand, the reserve canopy should preferably be released as soon as possible after the main canopy has been disconnected since time in this regard can be a critical factor. Conventionally, the harness connecting the main canopy to the container includes a mechanical release mechanism which is actuated by the parachutist to eject the main canopy, while the reserve canopy is released by a separate rip cord. Such an arrangement has the disadvantage that two separate operations are required by the parachutist, who must ensure that these operations are carried out in the correct order as indicated above, with the shortest possible time delay between the operations. However, especially for inexperienced parachutists, the possibility of a mistake or undue delay in carrying out these operations is a very real one and poses a significant danger.
It is important that the mechanism for disconnecting the main canopy be as rugged as possible to withstand the full load which may be imposed thereon and particularly the reaction force which develops when the main canopy opens and which may greatly exceed the parachutist's weight, while the mechanism should be as simple as possible to operate with minimal effort required of the parachutist and minimal stresses imposed on critical parts of the mechanism.
Conventionally the main parachute canopy is released by simultaneously disconnecting a pair of buckles which releasably connect the main parachute canopy to the harness. Generally, the buckles are actuated manually by the parachutist through a manual operator mounted on the harness. Due to the considerable load acting on the buckles the force required of the parachutist to actuate the release mechanism can be substantial. This makes it difficult for the parachutist to actuate release of the main canopy and presents a problem in obtaining reliable operation of the release mechanism. In U.S. Pat. No. 3,765,627 there is disclosed a system which seeks to overcome this problem by reducing the force required of the parachutist to release the buckle connection to the main parachute canopy. This is achieved, in accordance with the system disclosed in the U.S. Patent by providing a force multiplier between the release mechanism for the buckle and a handle which is pulled by the parachutist. The force multiplier essentially comprises a pulley system which effectively multiplies the force required to pull the handle by a factor of two. However, while this system reduces the force required of the parachutist, it does not reduce the actual forces acting on the release mechanism associated with the buckles. In this case, the force multiplier is connected to the buckle release mechanism by a cable, so that the full force required to actuate the release mechanism is transmitted through the cable. Accordingly, the cable and the various components associated with the release mechanism for the cable must be designed to withstand the full force normally required to actuate this kind of mechanism. Therefore, this system does not provide a fully satisfactory solution to the problem. Furthermore, the force multiplier is relatively bulky so that it has to be supported on a mounting plate mounted, for example, on the front of the harness.